It is known to cast a concrete counterfort, or more usually a pair of counterforts, with steel reinforcement projecting therefrom, and then once the concrete has hardened a facing is cast to form an integral unit with the counterfort(s). The shuttering for the facing must be accurately positioned and while this is time consuming there are further delays in waiting for the concrete which forms the facing to harden and in removing the shuttering. Further, since a typical wall has a height of 1O m it is not usually practical for the casting to take place in the final position of use. Thus each counterfort is normally arranged horizontally while the facing is cast and eventually the whole unit which has considerable weight must be lifted to the vertical position by a crane. At this stage it has been found to be virtually impossible to avoid small knocks which chip away the concrete at any corners and edges and lead to cracks and other imperfections. If the damage is excessive it is sometimes necessary to discard the whole unit. However these problems have been thought to be unavoidable in view of the requirement to erect a sound structure in which the counterfort and the facing form an integral reinforced concrete unit.